/*-------------------------------------------------------------------------
 *
 * amapi.h
 *      API for Postgres index access methods.
 *
 * Copyright (c) 2015-2017, PostgreSQL Global Development Group
 *
 * src/include/access/amapi.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef AMAPI_H
#define AMAPI_H

#include "access/genam.h"

/*
 * We don't wish to include planner header files here, since most of an index
 * AM's implementation isn't concerned with those data structures.  To allow
 * declaring amcostestimate_function here, use forward struct references.
 */
struct PlannerInfo;
struct IndexPath;

/* Likewise, this file shouldn't depend on execnodes.h. */
struct IndexInfo;


/*
 * Properties for amproperty API.  This list covers properties known to the
 * core code, but an index AM can define its own properties, by matching the
 * string property name.
 */
typedef enum IndexAMProperty
{
    AMPROP_UNKNOWN = 0,            /* anything not known to core code */
    AMPROP_ASC,                    /* column properties */
    AMPROP_DESC,
    AMPROP_NULLS_FIRST,
    AMPROP_NULLS_LAST,
    AMPROP_ORDERABLE,
    AMPROP_DISTANCE_ORDERABLE,
    AMPROP_RETURNABLE,
    AMPROP_SEARCH_ARRAY,
    AMPROP_SEARCH_NULLS,
    AMPROP_CLUSTERABLE,            /* index properties */
    AMPROP_INDEX_SCAN,
    AMPROP_BITMAP_SCAN,
    AMPROP_BACKWARD_SCAN,
    AMPROP_CAN_ORDER,            /* AM properties */
    AMPROP_CAN_UNIQUE,
    AMPROP_CAN_MULTI_COL,
    AMPROP_CAN_EXCLUDE
} IndexAMProperty;


/*
 * Callback function signatures --- see indexam.sgml for more info.
 */

/* build new index */
typedef IndexBuildResult *(*ambuild_function) (Relation heapRelation,
                                               Relation indexRelation,
                                               struct IndexInfo *indexInfo);

/* build empty index */
typedef void (*ambuildempty_function) (Relation indexRelation);

/* insert this tuple */
typedef bool (*aminsert_function) (Relation indexRelation,
                                   Datum *values,
                                   bool *isnull,
                                   ItemPointer heap_tid,
                                   Relation heapRelation,
                                   IndexUniqueCheck checkUnique,
                                   struct IndexInfo *indexInfo);

/* bulk delete */
typedef IndexBulkDeleteResult *(*ambulkdelete_function) (IndexVacuumInfo *info,
                                                         IndexBulkDeleteResult *stats,
                                                         IndexBulkDeleteCallback callback,
                                                         void *callback_state);

/* post-VACUUM cleanup */
typedef IndexBulkDeleteResult *(*amvacuumcleanup_function) (IndexVacuumInfo *info,
                                                            IndexBulkDeleteResult *stats);

/* can indexscan return IndexTuples? */
typedef bool (*amcanreturn_function) (Relation indexRelation, int attno);

/* estimate cost of an indexscan */
typedef void (*amcostestimate_function) (struct PlannerInfo *root,
                                         struct IndexPath *path,
                                         double loop_count,
                                         Cost *indexStartupCost,
                                         Cost *indexTotalCost,
                                         Selectivity *indexSelectivity,
                                         double *indexCorrelation,
                                         double *indexPages);

/* parse index reloptions */
typedef bytea *(*amoptions_function) (Datum reloptions,
                                      bool validate);

/* report AM, index, or index column property */
typedef bool (*amproperty_function) (Oid index_oid, int attno,
                                     IndexAMProperty prop, const char *propname,
                                     bool *res, bool *isnull);

/* validate definition of an opclass for this AM */
typedef bool (*amvalidate_function) (Oid opclassoid);

/* prepare for index scan */
typedef IndexScanDesc (*ambeginscan_function) (Relation indexRelation,
                                               int nkeys,
                                               int norderbys);

/* (re)start index scan */
typedef void (*amrescan_function) (IndexScanDesc scan,
                                   ScanKey keys,
                                   int nkeys,
                                   ScanKey orderbys,
                                   int norderbys);

/* next valid tuple */
typedef bool (*amgettuple_function) (IndexScanDesc scan,
                                     ScanDirection direction);

/* fetch all valid tuples */
typedef int64 (*amgetbitmap_function) (IndexScanDesc scan,
                                       TIDBitmap *tbm);

/* end index scan */
typedef void (*amendscan_function) (IndexScanDesc scan);

/* mark current scan position */
typedef void (*ammarkpos_function) (IndexScanDesc scan);

/* restore marked scan position */
typedef void (*amrestrpos_function) (IndexScanDesc scan);

/*
 * Callback function signatures - for parallel index scans.
 */

/* estimate size of parallel scan descriptor */
typedef Size (*amestimateparallelscan_function) (void);

/* prepare for parallel index scan */
typedef void (*aminitparallelscan_function) (void *target);

/* (re)start parallel index scan */
typedef void (*amparallelrescan_function) (IndexScanDesc scan);

/*
 * API struct for an index AM.  Note this must be stored in a single palloc'd
 * chunk of memory.
 */
typedef struct IndexAmRoutine
{
    NodeTag        type;

    /*
     * Total number of strategies (operators) by which we can traverse/search
     * this AM.  Zero if AM does not have a fixed set of strategy assignments.
     */
    uint16        amstrategies;
    /* total number of support functions that this AM uses */
    uint16        amsupport;
    /* does AM support ORDER BY indexed column's value? */
    bool        amcanorder;
    /* does AM support ORDER BY result of an operator on indexed column? */
    bool        amcanorderbyop;
    /* does AM support backward scanning? */
    bool        amcanbackward;
    /* does AM support UNIQUE indexes? */
    bool        amcanunique;
    /* does AM support multi-column indexes? */
    bool        amcanmulticol;
    /* does AM require scans to have a constraint on the first index column? */
    bool        amoptionalkey;
    /* does AM handle ScalarArrayOpExpr quals? */
    bool        amsearcharray;
    /* does AM handle IS NULL/IS NOT NULL quals? */
    bool        amsearchnulls;
    /* can index storage data type differ from column data type? */
    bool        amstorage;
    /* can an index of this type be clustered on? */
    bool        amclusterable;
    /* does AM handle predicate locks? */
    bool        ampredlocks;
    /* does AM support parallel scan? */
    bool        amcanparallel;
    /* type of data stored in index, or InvalidOid if variable */
    Oid            amkeytype;

    /* interface functions */
    ambuild_function ambuild;
    ambuildempty_function ambuildempty;
    aminsert_function aminsert;
    ambulkdelete_function ambulkdelete;
    amvacuumcleanup_function amvacuumcleanup;
    amcanreturn_function amcanreturn;    /* can be NULL */
    amcostestimate_function amcostestimate;
    amoptions_function amoptions;
    amproperty_function amproperty; /* can be NULL */
    amvalidate_function amvalidate;
    ambeginscan_function ambeginscan;
    amrescan_function amrescan;
    amgettuple_function amgettuple; /* can be NULL */
    amgetbitmap_function amgetbitmap;    /* can be NULL */
    amendscan_function amendscan;
    ammarkpos_function ammarkpos;    /* can be NULL */
    amrestrpos_function amrestrpos; /* can be NULL */

    /* interface functions to support parallel index scans */
    amestimateparallelscan_function amestimateparallelscan; /* can be NULL */
    aminitparallelscan_function aminitparallelscan; /* can be NULL */
    amparallelrescan_function amparallelrescan; /* can be NULL */
} IndexAmRoutine;


/* Functions in access/index/amapi.c */
extern IndexAmRoutine *GetIndexAmRoutine(Oid amhandler);
extern IndexAmRoutine *GetIndexAmRoutineByAmId(Oid amoid, bool noerror);

#endif                            /* AMAPI_H */
